From the perspective of preserving the global environment, power generating apparatuses of a renewable energy type such as a wind turbine generator using wind power and a tidal generator using tidal current, river current or ocean current energy are becoming popular. To improve power generation efficiency, it is desired to increase the size of the power generating apparatus of the renewable energy type. Particularly, wind turbine generators installed offshore are expensive to construct in comparison to those installed onshore and thus, it is desired to improve power generation efficiency by increasing the size of the wind turbine generator so as to improve profitability.
With increased output of the generator produced by the larger power generating apparatus of the renewable energy type, heat loss from the generator increases. In the power generating apparatus of the renewable energy type in which the rotation of the rotor is transmitted to the generator by a hydraulic transmission formed by a hydraulic pump and a hydraulic motor, in addition to the heat loss from the generator, there is heat loss from the hydraulic transmission as well. Thus, it is desired to develop a power generating apparatus of a renewable energy type having a function of cooling a heat-producing component such as the generator and the hydraulic transmission.
In view of this, Patent Literature 1 proposes a wind turbine generator having a cooling system for cooling a converter, a transformer and a control unit. The cooling system includes a plurality of heat exchangers installed around a tower. In the heat exchangers, a cooling medium having cooled the converter, the converter, the transformer and the control unit is cooled by heat exchange with atmospheric air.
Patent Literature 2 discloses a cooling device for a wind turbine generator. The cooling device has a heat exchanger to cool a plurality of devices such as a converter, a transformer, a bearing box and a generator. Cooling water cools the devices and then is cooled by the heat exchanger installed on an outer wall of a tower and a nacelle.